• Home
  • Download PDF
  • Order CD-ROM
  • Order in Print
HEAT TRANSFER FLUID CIRCULATION - TM-5-3895-374-24-2_280
heat exchanger

TM-5-3895-374-24-2 M081 Asphalt Mixing Plant Manual
Page Navigation
  232    233    234    235    236  237  238    239    240    241    242  
TM 5-3895-374-24-2 HEATER OPERATIONAL SAFEGUARDS CEI heaters are equipped with numerous safety controls to ensure a safe and reliable operating environment.  A brief discussion of each of these safeguards follows. LOW LEVEL CONTROL-ensures that the circulating pump and the burner will not operate if the heat transfer fluid level in the.  expansion tank is too low.  The LOW OIL light on the panel will also be lit. PUMP PRESSURE SWITCH-ensures positive  circulation  of  the  heat  transfer  fluid  before  the  burner  will  operate. For example, if there is water in the heat transfer fluid, then as the temperature of the fluid approaches 2120F, the water will be converted to steam and will expand.  This is potentially an extremely dangerous situation.  When the steam reaches the pump, the pump will lose pressure and the safety switch will prevent the burner from operating. FLAME SAFEGUARD SYSTEM-consists of the mini peeper, the flame amplifier module, program module and the heater operation programmer.  The main fuel supply is shut off and the FLAME FAILURE light on the panel box is lit if burner ignition fails.  Also, the normal operating cycle of the programmer includes a pre-purge and post-purge phase to ensure that no combustible gases remain in the firebox when burner ignition is attempted. PROOF-OF-CLOSURE SWITCH-on gas operation, ensures that the electric gas valve closed properly following the last burner cycle.  If the electric gas valve failed to close properly, the burner will not attempt to ignite. AIR FLOW SWITCH-on gas operation, ensures that the burner blower is mixing air in the firebox with the gas being supplied to the burner.  If not, the burner will not ignite and the programmer will continue to cycle. LOW FIRE START INTERLOCK-ensures that the burner is low-fire mode during ignition.  If not, ignition will not be attempted. HIGH  TEMPERATURE  LIMIT  SWITCH-shuts off the heater if the heat transfer fluid  temperature  reaches  450°F (575°F  for  heaters  set  for  high  temperature  operation).    This  switch  works  in  conjunction  with  the  temperature controller  which  has  a  set  point  limit  of  450°F  programmed  in  it  at  the  factory.    The  two  devices  provide  a temperature limit at two locations on the heater. TEMPERATURE  CONTROLLER-uses  a  thermocouple  to  indicate  the  heat  transfer  fluid  temperature  in  the circulating pump's pressure line.  If a thermocouple failure was to occur, the temperature controller would read the false signal as an infinite temperature and prevent operation of the heater. BY-PASS VALVE-ensures that heat transfer fluid will continue to circulate through the heater even if all external valves are closed.  This valve must remain open when the heater is operating. page 3-915







Western Governors University

Privacy Statement
Press Release
Contact

© Copyright Integrated Publishing, Inc.. All Rights Reserved. Design by Strategico.